Ocular Drug Delivery

In terms of ocular drug delivery, dendrimers have been shown to improve drug penetration into ocular tissues, including the cornea and retina. This is because dendrimers can bypass the various barriers that limit drug delivery, such as the blood-retina barrier, by crossing biological membranes through passive diffusion or receptor-mediated endocytosis.

Challenges in Ocular Drug Delivery

Ocular drug delivery presents unique challenges due to the complex anatomy and physiology of the eye. The eye is a highly specialized organ with a variety of different tissues, each with their own unique properties and challenges for drug delivery. Here are some of the challenges associated with ocular drug delivery:

• Limited Drug Penetration
  The eye has several protective barriers that limit drug penetration, such as the cornea, conjunctiva, and blood-retina barrier. These barriers can prevent drugs from reaching their intended target site, leading to reduced efficacy.
• Rapid Drug Clearance
  The eye has a high turnover rate of tears, which can quickly clear drugs from the ocular surface. This can limit the amount of time a drug is in contact with the targeted tissues, reducing its effectiveness.
• Difficulty in Targeting Specific Tissues
  The eye contains several tissues with different drug uptake mechanisms, making it challenging to target a specific tissue. For example, the sclera has poor vascularization, making it difficult to deliver drugs to this tissue.
• Patient Compliance
  Ocular drug delivery often requires frequent administration, which can be difficult for patients to adhere to. Eye drops can be challenging to administer, and other delivery methods such as intraocular injections or implants require a skilled healthcare provider.
• Formulation Challenges
  Ocular drug delivery requires specialized formulations that can maintain drug concentration and stability, while also ensuring that the drug is biocompatible and non-toxic to the eye.

Dendrimer May be a Valuable Tool for Ocular Drug Delivery

The ocular route of drug administration has several advantages, including a high concentration of target tissue, limited systemic absorption, and avoidance of first-pass metabolism. However, the ocular barriers, such as the cornea, conjunctiva, and blood-retina barrier, limit drug penetration into the ocular tissues. Dendrimers can overcome these barriers by their small size, high surface area to volume ratio, and ability to cross biological membranes. Dendrimers can be modified to improve their biocompatibility, reduce toxicity, and enhance drug release. Surface functionalization with polyethylene glycol (PEG) can increase the circulation time of dendrimers in the body and reduce their immunogenicity. In addition, the surface of dendrimers can be modified with targeting moieties to improve their tissue specificity and enhance drug delivery to the desired site. Several dendrimers have been studied for ocular drug delivery, including polyamidoamine (PAMAM), poly(propyleneimine) (PPI), and poly(l-lysine) (PLL) dendrimers.

Schematic depicting the latest advancement in multiple ocular drug delivery systems. (Kim HM, Woo SJ. 2021)

As a fast-growing custom service provider specializing in dendrimer research, CD BioSciences is dedicated to helping you develop dendrimers for ocular drug delivery.

How We Can Help

CD BioSciences is committed to accelerating the pace of dendrimer development and its applications to greatly improve its use in the biomedical field. With our deep knowledge and experience in dendrimer research, we are committed to providing high quality products and customized services to our customers. If you are interested in our services, please contact us.

Reference

1. Kim HM.; Woo SJ. Ocular Drug Delivery to the Retina: Current Innovations and Future Perspectives. Pharmaceutics. 2021, 13: 108.